Waterproof fiberboard



March 4, 1958 H. J. ROUX 2,825,660

WATERPROOF FlBERBOARD Filed Dec. 50, 1954 ASPHALT RUBBER-ALGNATE COATI NG F IBERBOARD INVENTOR HENRY J. ROUX ATTORNEY United States PatentWATERPROOFFIBERBOARD Henry J. Roux, Lancaster, 'Pa., .assignor toArmstrong Cork Company, Lancaster, Pa., a Corporation of PennsylvaniaApplication December30, 1954, Serial No. 478,910

2 Claims. (Cl. 117-1355) This invention relates to awaterproof,vapor-permeable insulation board and method of producing the same, and

more particularly to a conventional "fiberboard insulation producthaving applied thereto a film of coating material which will resist thepenetration of water into the board .ing the outer walls of thebuilding. This sheathing-is usually in place for a period of timebeforethe-exterior finishof the building is put in place over the sheathing.

During this period of time,the sheathing is exposed to the weather; andif the material is not 'weatherproofed, the

insulationbeco'mes waterlogged and the insulating value is greatlydiminished. In order to overcome this, it has been common practice toapply a film of asphalt to the surface of the sheathing material. Thisfilm of asphalt is Waterproof and renders the sheathing resistant torain when exposed to the elements; however, the asphalt coating is alsovapor-impermeable, and thereby prevents the passage of moisture from theinterior of the building through the insulating material to the outsideof the building. This waterproof coating is applied to the outside ofthe insulating sheathing and, therefore, forms a vapor barrier at theouter surface of the sheathing, which means that the moisture condensesin the sheathing, thereby diminishing its insulating value. This hasbeen overcome to a certain extent by applying a relatively hard asphaltcoating, and depending on the heavy brittle coating, cracking upondrying, leaving small fissures through which moisture can escape. Thisis a rather haphazard arrangement, however, and the transmission ofvapor through the fiberboard is diminished somewhat by this type ofcoating.

The invention set forth in this application is directed to a fiberboardmaterial in which a film of asphalt emulsion and rubber latex, togetherwith an alginate, is applied to the surface of the insulating board atthe time the board is produced on a conventional Web-forming fiberboardmachine. This film of asphalt emulsion and rubber latex with thealginate renders the fiberboard resistant to water from the elements butrenders the surface of the board vapor-permeable so that moisturetransmitted from the interior of the building can pass freely throughthe fiberboard to the exterior. As a matter of fact, the transmission ofthe vapor through the board is not diminished to any appreciable extentbecause of the coating.

An object of this invention is to provide an insulating sheathing havingapplied thereto a waterproof, vaporpermeable coating which will renderthe insulation resistant to waterlogging caused from exterior water andwill at the same time render the board vapor-permeable to permit theready transmission of vapor through the board.

Another object of this invention is to provide a method acoating fortheasphalt particles. =aidsin'renclering the coating water repellent.

2,825,650 Patented Mar. 4, 1958 ofproducingsa fiberboard with awaterproof, vapor-permeable coating by the application of a coatingcomprisingiasphalt emulsion, rubber latex, and an alginate'at the wetendof the fiberboard forming machine.

In .carryingout the invention, it has been foundthat soap type asphaltemulsion is best suited for producing the desired results. The rubberlatex may be any of the conventional synthetic or natural rubber laticesand the alginate .may be any of the conventional commercially availablealginates,'such as, for example, Keltex, which is a sodium :derivativeof-algin and is one of the complex organic alginates.

I have rfound'that. a suitable formulation for carrying out theinvention is as follows:

Dow latex 512K (60% styrene and 40% butadiene)- 25 -Keltex (sodiumderivative of alginate) 1.5

Dowicide G (sodium. salt of pentachlorophenol)--- 0.2

In-theabove formulation, the asphalt emulsion, which .forms .a majorproportion of the coating, renders the coating water resistant and alsohelps to adhere the coat- .ingto the fiberboard. The latex 512K, whichis a copolyruercomprising 60% styrene and 40% butadiene, forms Therubber latex also While-in the examplegiven the rubber latex is a:styrene-butadiene type latex, it will beunderstood that; any of theconven- .tional.syn thetic rubber latices or natural rubber latices aresuitable for carrying out the invention. Therubber latex should bepresent in a quantity sufficient to coat the asphalt particles. Thepreferred range of rubber latex to asphalt emulsion has been found to bebetween .05 to .3 rubber latex compared to the quantity of asphaltemulsion used.

The Keltex, which is a sodium derivative complex organic alginate,serves as a web for adhering the latex coated asphalt particlestogether. This forms a coating which is smooth but not continuousbecause of the extremely small interstices distributed uniformlytherethrough. These interstices are of such a nature that the watercoming in contact with the exterior of the board will not penetrate theboard through the interstices but the interstices permit vapor to passtherethrough as vapor pressure is built up in the board caused by vaporpressure differentials between the interior and the exterior of theboard. For best results, the Keltex should be present in an amountranging from .005 part to one part of asphalt emulsion to .01 part toone part of asphalt emulsion. The Dowicide G, which is a sodium salt ofpentachlorophenol, is present as a preservative for the Keltex and therubber latex. Any of the conventional preservatives for rubber latex aresuitable for carrying out this purpose.

The attached drawing illustrates a piece of fiberboard with thewaterproof vapor-permeable coating applied thereto.

In the application of the coating to the fiberboard, it has been foundthat the most expeditious way to apply the coating is to apply it at thewet end of the boardforming machine. When this is done, both the coatingand the board can be dried simultaneously by one passage through thedrier. If the coating is applied after the board has been formed anddried, it is necessary to utilize hot melt equipment on the applicationof a coating of asphalt to the surface of the board. The above coatingcould be applied to the dry board; however, an additional drying stepwould be involved and considerable assumes time and expense can be savedif the coating is appliedat. a

the wet end of the board-forming machine. 7 In the application ofcoatings at the wet end of the board-forming"process,; the problem: ofdiffusioncof the coating material through'ithe wet board is ofconsiderable importance; Most coatings'appliedarthe wet end'diifus'efreely through the board and coat the:fibers substantially :uniformlythroughout the board.thickness;' \Thisiis a 2.

' .place because of the web structure which is formedby the 'alginateadheringcthe' rubber-coated iasphaltt'pa'rticles to one another. Thisweblike structure prevents undueidiffusion :into the board andthe-coating;is merely .applied to the surface of the wet board; 1 5i if?The coating is preferably applied to the wet board from a pool which isdisposed back of a roller which engages :the surface of the board with aslight amount of pressure. Thewet board moves'through under thereservoir of coating material and the excess coating material-is removedby means of the roller which appliesa slight amount of pressure to thesurface of the wet board. After the board .moves beyond the point atwhich the roller applies pressure, the board springs back to itsoriginal thickness and the thin film of coatin'g'mater'ial is applieduniformly to --the surface of the boards This-is only one of the many'systems which may be utilized for the application'of the coatingcomposition to the board at the wet end of-the board-forming machine; Itwill be-unde rsto od that the coating material could be sprayeddirectly'onto the finishedweb as it moves between'the forming machineand the drier, andcalso the coating may be applied by means of aprinting device coming in contact with the surface of the newly formedboard ash is mov' g between the forming machine and the drier. r

As, the. board is removedrfrom the .dryingcequipment; 7

the surface is coated witha thin film of black coating material whichrenders the board waterproof; however, the coating does not diminish thetransmission of vapor through theboard to any appreciable extent.

Iclaim: i s. 2 1

1. As an article of manufacture, an insulation board composed of mattedand entangled fibers, said board having a normal heat insulatingyalueand a coating adhering to saidrboard to 'render said board waterproofand vapor-permeable without material difiusion of the coating into theinterior of said board so as to alter substantially its normalheatiinsula'ting value and vapor permeability, said coating comprisingamixture of asphalt, rubber, and a water-soluble alginate.

2. As an article of manufacture, an insulation board composed of mattedand entangled fibers, said board having a normal heat'insulating valueand.;a coatin'gadherving to said board tosrender said board waterproofand vapor-permeable withoutmaterial diffusion into the interior of'saidboard soasinot to alter substantially its normal heat insulating valueand vapor permeability,'fsaid coating'comprisinga mixture of partsasphalt,-10 to I .30parts rubberyand 05 m2 parts of a, water-solublealginate.

Referenc es'Cited -in-the file of this patent UNITED STATES PATENTSErdahl May '9, 1922 I 2,105,825 Smith Jan. 13,1933 7 2,210,348 SwopeAug. 6, 1940 2,393,022 Jan. 15,1946 2,701,219 Fair Feb. 1, 1955Christensen Apr. 2, .1957

1. AS AN ARTICLE OF MANUFACTURE, AN INSULATION BOARD COMPOSED OF MATTEDAND ENTANGLED FIBERS, SAID BOARD HAVING A NORMAL HEAT INSULATING VALUEAND A COATING ADHERING TO SAID BOARD TO RENDER SAID BOARD WATREPROOF ANDVAPOR-PERMEABLE WITHOUT MATERIAL DIFFUSION OF THE COATING INTO THEINTERIOR OF SAID BOARD SO AS TO ALTER SUBSTANTIALLY ITS NORMAL HEATINSULATING VALUE AND VAPOR PERMEABILITY, SAID COATING COMPRISING AMIXTURE OF ASPHALT, RUBBER, AND A WATER-SOLUBLE ALIGNATE.